1. Field of the Invention
The present invention relates generally to fluid operated devices and, more particularly, to a fluid operated device with improved sealing means.
2. Description of the Prior Art
There have been previously known fluid operated devices comprising an elongated housing defining an elongated cylinder and in which a piston is longitudinally slidably mounted. Furthermore, the piston defines a chamber between one end of the piston and one end of the housing and a second chamber between the other other end of the piston and the other end of the housing. Consequently, pressurization of one chamber moves the piston in one direction along the cylinder while, conversely, pressurization of the other chamber moves the piston in the opposite direction.
In some applications, for example, when the fluid operated device is utilized to operate the window of a motor vehicle, an elongated slot is formed along one side of the housing which is open to the cylinder. The piston then includes an arm which protrudes outwardly through the slot and is attached to the window of the motor vehicle. Consequently, movement of the piston simultaneously moves the window with it.
Since the housing slot is necessary to connect the piston to the vehicle window, however, it is necessary to sealingly close the slot along the chambers regardless of the position of the piston. Otherwise, pressurization of either, chamber would simply result in the fluid escaping through the housing slot.
It has been the previous practice to secure an elongated band which is routed under the piston arm but which otherwise flatly abuts against and covers the housing slot along the chambers. Thus, the band still permits the piston to longitudinally slide along the cylinder but provides a fluid seal of the slot along the cylinder chambers. Since such fluid operated devices are typically pneumatically operated, some air leakage through the housing slot is insignificant.
One disadvantage of these previously known devices, however, is that the band in relatively large stroke cylinders tends to fall away from the slot because of self weight and leak, and even a relatively small deformation of the band seal can cause a large air leakage from the chambers and render the entire fluid operated device inoperable.